Regulation of sequentially operating light source and device for carrying out the method

ABSTRACT

The present invention refers to a method and a device for sequentially operating light source, in particular a lighting system for signalizing a change of driving direction of a motor vehicle, comprising a plurality of light emitting diodes (LED) connected in series, said diodes can be activated in a pre-determined sequence within a required time frame t0. The method comprises activating within a required time frame (t0) a sequential operation of a plurality of LEDs, wherein the operation of the first LED in the plurality of LEDs and operation of the last LED in the plurality of LEDs is carried out within an actual time frame (t1) of operation. The method further comprises activating after lapse of a safety time frame (t2) of all LEDs (11, 12 . . . 1n) simultaneously.

The present invention refers to a method and a device for sequentiallyoperating light source, in particular a lighting system for signalizinga change of driving direction of a motor vehicle, comprising a pluralityof light emitting diodes connected in series, said diodes can beactivated in a pre-determined sequence.

Light systems for signalizing driving direction of a motor vehicle,comprising a plurality of light emitting diodes (LED) connected inseries, said diodes can be activated in a pre-determined sequence arewell known from various patent applications such as DE 10 2015 010 315A1, CN 104816668 A, US 2015/0158416 A1, US 2013/0127612 A1, US2009/0051523 A1, JP 2005132256 A, for example. None of said documents,however, disclose how to operate a sequentially operating light in orderto enable a reliable functional safety of the lighting system operation.In case of a sequential circuit failure only the first LED from theplurality of LEDs would be operational in the worst scenario, however,the failure would not be detected by a vehicle diagnostic which isabsolutely unacceptable from the functional safety point of view. Inorder to remedy said problems, most of the known solutions focus eitherto duplicating the control circuit or to duplicating the light sourcesor to the combination thereof.

It is the object of the present invention to create a method ofsequentially operating light source, particularly with a motor vehicle,which enables a reliable functional safety of a lighting systemoperation. The invention further refers to a device for carrying outsaid method.

The object as set above is solved, according to the present invention,by features according to the characterising clause of the claim 1. Theinvention is disclosed in detail in corresponding subclaims.

The invention is further described in detail by way of non-limitingembodiment, and with a reference to the accompanying drawing, whichshows a schematic view of a device for enabling a functional safetyaccording to the invention.

A detailed description of the invention is based on the embodimentrepresenting a device for sequentially operating lighting system forsignalizing a change of driving direction of a motor vehicle and,respectively, a so called direction indicator. Said direction indicatorcomprises a plurality of light emitting diodes 1 ₁, 1 ₂ . . . 1 _(n)(LED) connected in series, that are controlled by means of a feedingdevice, such as a DC/DC converter or a plurality of constant currentsources 2 ₁, 2 ₂ . . . 2 _(m), as provided for in the presentembodiment, and similar. The number n of LEDs is preferably, yetnon-limiting, selected as an even number. When the number n of LEDs isselected as the even number, a single current source 2 ₁, 2 ₂ . . . 2_(m) is assigned per each pair 1 ₁, 1 ₂; 1 ₃, 1 ₄ . . . 1 _(n-1), 1 _(n)of the LEDs, whereby the direction indicator is attached by means of aconnecting element in a manner know per se to the wiring of theheadlamps. In the present embodiment, the number m of the currentsources 2 ₁, 2 ₂ . . . 2 _(m) preferably equals to n/2. Energy is fed tosaid direction indicator via an input protecting element 3, whichprotects direction indicator against possible polarity reversal,electrostatic impulse, voltage pulse, and similar.

Moreover, said circuit is provided with a thermal protection element 4,the resistance thereof varies in dependence of temperature. When thetemperature on said circuit reaches a critical value, said thermalprotection element 4 lowers the current fed. The luminosity decreasesconsequently, thus, keeping the electronic components in permittedtemperature ranges.

Said circuit is further provided with an excess voltage protectionelement 5, which in case of excessive voltage, in the present embodimentthe voltage >19V, switches off the entire circuit of the directionindicator. In addition, a security element 6 is provided on said circuitwhich, in case that at least one LED 1 ₁,1 ₂ . . . 1 _(n) in from theplurality of LEDs fails, provides for that the diagnostic system in thevehicle alerts a driver about the failure.

In addition to said elements, said circuit of the direction indicatoralso comprises a timer and shift element 7, which takes care of thesequential lighting of LEDs 1 ₁, 1 ₂ . . . 1 _(n) and a control element8, which connects all aforesaid elements and takes care of therespective functions thereof are carried out. A switch 9 ₁, 9 ₂ . . . 9_(k) is allocated to each second LED 1 ₂, 1 ₄ . . . 1 ₁ from theplurality of LEDs 1 ₁, 1 ₂ . . . 1 _(n). The number k of switches 9 ₁, 9₂ . . . 9 _(k) preferably equals to the number m of the current sources2 ₁, 2 ₂ . . . 2 _(m), which preferably equals to n/2. At the beginningof the operation, when the energy is fed to the direction indicator allswitches 9 ₁, 9 ₂ . . . 9 _(k) are closed, wherein only the firstcurrent source 2 ₁ is turned on activating thus the operation of thefirst LED 1 ₁ from the plurality of LEDs 1 ₁, 1 ₂ . . . 1 _(n). In thenext sequence, the timer and shift element 7 opens the first switch 9 ₁,whereby the second LED 1 ₂ is activated. Afterwards, the second currentsource 2 ₂ is turned on and the process repeats with the next pair ofLEDs 1 ₃, 1 ₄ from the plurality of LEDs 1 ₁, 1 ₂ . . . 1 _(n).

It is provided for according to the present invention, that a reservesecurity element 10 is attached to the control element 8, which takescare of operating the direction indicator when an error occurs and,respectively, at the failure any of the components of the directionindicator. Sequentially operating lighting system for signalizing changeof driving direction operates in a required time frame t₀, whichtypically amounts to less or equal to 200 ms. In said time frame t₀ arequired number of LEDs must be sequentially activated, preferably allLEDs 1 ₁, 1 ₂ . . . 1 _(n), from the first LED to the last one. After alapse of a safety time frame t₂, which is smaller or at most equal tosaid required time frame t₀, but larger from or at least equal to anactual time frame t₁ of lighting all LEDs 1 ₁, 1 ₂ . . . 1 _(n) from theplurality of LEDs, the reserve security element 10 provides forreactivating all LEDs 1 ₁, 1 ₂ . . . 1 _(n) from the plurality of LEDs,but this time all simultaneously. Thus, the direction indicatoraccording to the present invention operates in a manner, that the LEDs 1₁, 1 ₂ . . . 1 _(n) at first light sequentially, and within the safetytime frame t₂ also all simultaneously.

Said actual time frame t₁ of lighting all LEDs 1 ₁, 1 ₂ . . . 1 _(n)from the plurality of LEDs can be at most equal or smaller with respectto said required time frame t₀ and is typically selected in the rangebetween 130 ms and 150 ms. When simultaneously all LEDs 1 ₁, 1 ₂ . . . 1_(n) from the plurality of LEDs are activated, said safety time frame t₂is smaller or at most equal to said required time frame t₀, andsimultaneously larger than or at least equal to said actual time framet₁ of the lighting all LEDs 1 ₁, 1 ₂ . . . 1 _(n) from the plurality ofLEDs, wherein the safety time frame t₂ is typically selected in therange between 150 ms and 190 ms.

When the direction indicator and, respectively, the device for providingfunctional safety according to the invention operates flawless, than theprocess of activating LEDs is carried out in the required sequentialmanner. If, however, any error occur on the circuit of the directionindicator and, respectively, any component of the direction indicatorfails to operate, the process of activating LEDs is carried out in amanner, that at first LED 1 ₁ is activated, and after a lapse of thesafety time frame t₂ all other LEDs are activated simultaneously. In thefollowing, the invention is represented on the basis of two examples.

EXAMPLE 1 Failure of the Timer and Shift Element

When the direction indicator is turned on the first LED 1 ₁ in theplurality of LEDs is always activated, whereas remaining LEDs 1 ₂, 1 ₃ .. . 1 _(n) are not activated due to said non-operation of the timer andshift element 7. In this particular case, said reserve security element10 provides for by means of overriding all other circuits and,components, that all LEDs are activated simultaneously within the safetytime frame t₂≤t₀ oz. t₂≥t₁.

EXAMPLE 2 Failure of One of the LEDs

If anyone of LED 1 ₁, 1 ₂ . . . 1 _(n) from the plurality of LEDs fails,such as LED 1 ₃ for instance, the security element 6 stores theinformation about a limited failure of the LED 1 ₃ and all LED are notactivated until the end of the sequence. The LEDs remain non-activatedfor the entire time frame within which the direction indicator issupposed to operate. The diagnostic takes place since the LEDs are notactive and, thus, there is no power consumption and, respectively, thepower consumption decreases.

1. A method for sequentially operating light source on a vehicle, inparticular a lighting system for signalizing a change of drivingdirection of a motor vehicle, comprising a plurality of light emittingdiodes (LED) (1 ₁, 1 ₂. . . 1 _(n)) connected in series, said diodes canbe activated in a pre-determined sequence within a required time frame(t₀), characterized in that, the method comprises the following steps:a) activating within a required time frame (t₀) a sequential operationof a plurality of LEDs (1 ₁, 1 ₂ . . . 1 _(n)), wherein the operation ofthe first LED (1 ₁) in the plurality of LEDs and operation of the lastLED (1 _(n)) in the plurality of LEDs is carried out within an actualtime frame (t₁) of operation; b) activating by means of a reservesecurity element and after lapse of a safety time frame (t₂) of all LEDs(1 ₁, 1 ₂ . . . 1 _(n)) simultaneously.
 2. The method according to claim1, wherein the required time frame (t₀), the actual time frame (t₁) andthe safety time frame (t₂) are equal.
 3. The method according to claim1, wherein said actual time frame (t₁) is at most equal to or smallerthan the required time frame (t₀).
 4. The method according to claim 1,wherein said safety time frame (t₂) is equal to or smaller than therequired time frame (t₀), but larger than the actual time frame (t₁) ofthe activation of all LEDs (1 ₁, 1 ₂ . . . 1 _(n)).
 5. A device forcarrying out a method according to claim 1, characterized in that, thedevice comprises: a) a plurality of light emitting diodes (1 ₁, 1 ₂ . .. 1 _(n)) connected in series; b) a feeding device which that controlsat least one LED from the plurality of LEDs (1 ₁, 1 ₂. . . 1 _(n)); c) athermal protection element the resistance thereof depends ontemperature; d) an excess voltage protection element; e) a securityelement, which in case that at least one LED (1 ₁, 1 ₂. . . 1 _(n)) fromthe plurality of LEDs fails provides for that a driver is alerted aboutthe failer; f) a timer and shift element, which provides for asequential activation of LEDs (1 ₁, 1 ₂ . . . 1 _(n)); g) a controlelement, which connects all aforementioned elements and provide forcarrying out of respective functions thereof; and h) a reserve securityelement, which is associated with the control element and takes care ofthe operation when the failure occurs and, respectively, when any of thecomponents fails.
 6. The device according to claim 5, wherein the numbern of LEDs is selected as an even number.